Restrict fcuda-is-device to NVPTX targets and add a comment

Author: Georgi Mirazchiyski

clang/lib/Driver/ToolChains/HIPAMD.cpp

@@ -23,6 +23,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
 #include "llvm/TargetParser/TargetParser.h"
+#include "llvm/TargetParser/Triple.h"
 
 using namespace clang::driver;
 using namespace clang::driver::toolchains;
@@ -283,7 +284,9 @@ void HIPAMDToolChain::addClangTargetOptions(
           DeviceOffloadingKind == Action::OFK_SYCL) &&
          "Only HIP and SYCL offloading kinds are supported for GPUs.");
 
-  if (DeviceOffloadingKind != Action::OFK_SYCL)
+  // If we are compiling SYCL kernels for Nvidia GPUs throuh HIP, we do not
+  // support Cuda device code compatability, hence we do not allow Cuda mode.
+  if (getTriple().isNVPTX() && DeviceOffloadingKind != Action::OFK_SYCL)
     CC1Args.push_back("-fcuda-is-device");
 
   if (!DriverArgs.hasFlag(options::OPT_fgpu_rdc, options::OPT_fno_gpu_rdc,